Wireless telephone systems, which are a type of duplex or two-way communication system, have become widely deployed throughout the United States and abroad. In the United States, most service areas have a number of competing types of wireless communication services for customers to choose from. These include the original analog system or Advanced Mobile Phone System (“AMPS”) operating with a carrier frequency in the region of 800 MHz (“Cellular band”) as well as digital encoding protocols, such as, Time-Division Multiple Access (“TDMA”), Global System for Mobile communication (“GSM”), and Code-Division Multiple Access (“CDMA”), which operate both in the Cellular band and the Personal Communication System (“PCS”) frequency band region of 1900 MHz. Wireless telephone service is also widely available using the European digital systems operating in a carrier frequency band of 900 MHz (“GSM900”) or the 1800 MHz Digital Communication System (“DCS”) band using GSM encoding (and GPRS/EDGE) and the 2100 MHz Universal Mobile Telephone System (“UMTS”) band using CDMA encoding.
All of these wireless telephone systems can suffer from a loss of service in areas where the propagating communication signals are weak due to distance from the Base Transceiver Station (“BTS” or “cell tower”) and/or because the signal is blocked by structures or other obstructions. For large buildings and terrestrial features, such as hills and mountains, this problem is addressed by strategic placement of cell towers, which at this point can be seen in a line of site from almost anywhere in the United States. But indoors, where the building blocks the propagating communication signals, it is impractical for the service provider to attempt to solve the problem in all buildings by deploying additional BTSs. For large buildings, it may be practical to locate a dedicated BTS antenna to provide a strong communication signal throughout much of the building, but not for most homes and small offices.
In most homes and small offices, it is not feasible for the users to obtain a dedicated BTS antenna. In this situation, it is not cost effective for the service provider to locate a BTS antenna or increase the transmission power to satisfy individual customers with indoor reception problems. For example, when service is poor in certain locations within the customer premises, such as an office in the basement, there is no practical way to obtain a strong communication signal from a cell tower. As a result, wireless repeaters suitable for receiving, amplifying and retransmitting the wireless communication signal to a specific location, such as an office located in the basement of the customer premises, have been developed and have met with a certain amount of commercial success.
In order to meet the widespread need for improved wireless coverage in homes and small-offices, a wireless repeater must be cost-effective, simple to use, easy to install, and safe for the service provider's network. In order to accomplish these requirements, a wireless repeater must satisfy several challenges. First, the wireless repeater system should be universal to protocol and modulation; therefore, it must be able to handle communications for the AMPS, TDMA, CDMA and GSM systems in a cost-effective manner in the appropriate frequency band (Cellular, PCS, GSM900, DCS, UMTS etc.). Second, the wireless repeater system has to be relatively easy to install by the non-technical customer or professional installation must be widely available at a reasonable cost (typically less than half of the equipment cost). Third, the system must be able prevent interference with the Cellular or PCS network, including positive feedback (“self-oscillations”) which develops between the two antennas of the wireless repeater system. This type of self-oscillation, similar to that experienced in audio systems when the microphone is placed too close a speaker, can cause serious problems within the wireless network, including reduced capacity, reduced effective coverage, and loss of service to other licensed users. Also, if not checked, an oscillation within the wireless repeater system can lead to destruction of its circuitry. Fourth, the system should be able to handle communication signals from both relatively near base stations (i.e., relatively strong signals) and relatively far base stations (i.e., relatively weak signals) without creating disruptive interference. Fifth, the system should be able to handle communication signals from both relatively near mobile stations (i.e., relatively strong signals) and relatively far mobile stations (i.e., relatively weak signals) without creating disruptive interference.
Accordingly, there is an ongoing need for a wireless repeater system that is cost-effective for home-based and small office locations. There is a further need for a cost-effective wireless repeater system configured to meet the presently experienced needs for such a system, including the ability to handle the several different types of communication signals that are presently in use, to detect and prevent low-level self-oscillations, to be easy to install or easy to have professionally installed, and to control power transmission from near and far base stations and from near and far mobile stations.